最简单的电话由话筒和听筒组成，其中 ____能把声信号转化为电信号．固定电话 的声音信息是由导线中的电流来传递的，而移动电话的声音信息却是由 ____来传递的．

     Mr. Jackson is a teacher of science in a middle school. His students like his classes because his classes are very interesting. They can learn a lot in his class. The students can make（制作）many things. His little son Val also likes making things. He makes lots of machines（机器）, such as a machine like a man. It can do the job that is dangerous（危险的）for people to do. He says, “I want to be a scientist.”
根据短文内容，选择正确答案。

台湾发展外向型经济有利的自然条件是（ ）